| 摘要 |
PROBLEM TO BE SOLVED: To form a gate oxide of different thickness easily on a single chip by implanting a dopant into a first region and a dopant of different dosage into a second region thereby growing an oxide in the first region and an oxide of different thickness in the second region. SOLUTION: Nitrogen ions are implanted into the surface of a substrate in section A through a pad-like oxide layer 26 until a dosage of about 5×10<14> /cm<2> is reached, for example. The silicon surface in section A implanted with nitrogen ions is then exposed to an oxidizing atmosphere and a gate oxide layer of about 40Åis grown on the surface of the substrate. Subsequently, nitrogen ions are implanted into section B of the substrate 10 through the exposed pad-like oxide layer 26. Nitrogen ions are implanted at a dosage of 2×10<14> /cm<2> , for example. Subsequently, the silicon surface in section B implanted with nitrogen ions is exposed to an oxidizing atmosphere and a gate oxide layer of about 75Åis formed.
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